Analysis of variance (ANOVA) is one of the most frequently used statistical methods in medical research. The need for ANOVA arises from the error of alpha level inflation, which increases Type 1 error probability (false positive) and is caused by multiple comparisons. ANOVA uses the statistic F, which is the ratio of between and within group variances. The main interest of analysis is focused on the differences of group means; however, ANOVA focuses on the difference of variances. The illustrated figures would serve as a suitable guide to understand how ANOVA determines the mean difference problems by using between and within group variance differences.
Analysis of Variance* ; False Positive Reactions ; Inflation, Economic

Frozen section diagnosis is a highly useful method of diagnosis. There were 4434 frozen sections, 24 false positive diagnosis, 65 false negative diagnosis and 30 deferred diagnosis. This method achieves the highest accuracy when there is a cooperation between experienced surgeon and reliable and careful pathologist. It is wise to defer the diagnosis of consult to other pathologist in difficult situation.
Biopsy/*standards ; False Negative Reactions ; False Positive Reactions ; *Frozen Sections ; Humans ; *Microtomy ; Neoplasms/*diagnosis/pathology ; *Predictive Value of Tests

We messured delayed cutaneous hypersensitivity reactions by Multitest CMI Kit. Total 209 normal adults ranging in age from 17 to 55 year(male 106, female 103) were tested. The results were obtained as follows ; 1. Sum of average diameter of positive antigens wss 20.7mm in male and 15.6mm in female. 2. Number of positive antigens was 3.9 in male and 3.4 in female. 3. Rate of anergy was 1.4%(0.9% in male, 1.9% in female). 4. The rate of subjects below warning score(below 10mm in male, below 5mm in female) was 2.8% in male and 5.8% in female. 5. Antigen with the highest response was tuberculin in both sex(male 95.3%, female 89.3%) and antigen with the lowest response was trichophyton(22.5%). 6. Aversge score of positive response of every antigens was highest in tuberculin at both sex(male 2.8mm, female 2,6mm) 7. Average score of total antigens with positive response was 5.5mm in male and 4.6mm in female. 8. The rate of false positive reaction to 70% W/V glycerine was 1.4% totally.
Adult* ; False Positive Reactions ; Female ; Glycerol ; Humans ; Hypersensitivity* ; Korea* ; Male ; Tuberculin

BACKGROUND: We evaluated the performance and false positive rate of Mediace RPR test (Sekisui, Japan), a newly introduced nontreponemal test using a chemistry autoanalyzer. METHODS: The sensitivity of Mediace RPR test was analyzed using sera from 50 patients with syphilis in different stages (8 primary, 7 secondary, and 35 latent), 14 sera positive with fluorescent treponemal antibody absorption (FTA-ABS) IgM, and 74 sera positive with conventional rapid plasma regain (RPR) card test (Asan, Korea) and also positive with Treponema pallidum hemagglutination (TPHA) test or FTA-ABS IgG test. The specificity was analyzed on 108 healthy blood donors. We also performed RPR card test on 302 sera that had been tested positive with Mediace RPR test and also performed TPHA or FTA-ABS IgG test to analyze the false positive rate of Mediace RPR test. A cutoff value of 0.5 R.U. (RPR unit) was used for Mediace RPR test. RESULTS: Mediace RPR test on syphilitic sera of different stages (primary, secondary, and latent stages) and FTA-ABS IgM positive sera showed a sensitivity of 100%, 100%, 82.9% and 100%, respectively. Among the 74 sera positive with conventional RPR card test and TPHA or FTA-ABS IgG test, 55 were positive with Mediace test. The specificity of Mediace RPR test on blood donors was 97.2%. Among the 302 sera positive with Mediace RPR test, 137 sera (45.4%) were negative by RPR card and TPHA/FTA-ABS IgG tests. CONCLUSIONS: Although the sensitivities of Mediace RPR were good for primary and secondary syphilis, due to its high negative rate of Mediace RPR over the conventional RPR positive samples, further studies are necessary whether it can replace conventional nontreponemal test for screening purpose. Moreover, in view of the high false positive rate, positive results by Mediace RPR test should be confirmed with treponemal tests.
Autoanalysis/methods ; False Positive Reactions ; Humans ; ROC Curve ; Sensitivity and Specificity ; Syphilis/*diagnosis ; Syphilis Serodiagnosis/*methods

Immunohistochemical study with carcinoembryonic antigen (CEA) by peroxidase-antiperoxidase (PAP) method in rat bladder tumor induced by administration of N-butyl-N-( 4-hydroxybutyl)- nitrosamine was performed to know the immunological cross reactivity between human bladder tumor and experimentally induced rat bladder tumor and to evaluate, if all, its role as an indicator of malignant potential in rat bladder tumor. The results revealed 6 false positive reactions regardless of their histologic types and gave us no meaningful informations about ongoing disease process.
Animals ; Carcinoembryonic Antigen* ; False Positive Reactions ; Humans ; Rats ; Urinary Bladder Neoplasms* ; Urinary Bladder*

OBJECTIVETo explore the impact of misclassification in binary explanatory variables on the effects associated with 'exposure-disease'.

METHODSBased upon the functions of probabilities on misclassification, effects of association and proportions of exposure, the 'R Project for Statistical Computing' method was used to analyze the impact of misclassification on the validity of a study.

RESULTSTo the linear model case, the effect of nondifferential misclassification serves as an attenuating bias. When r = 0.5, the bias is symmetric in both sensitivity and specificity but when r is not equal to 0.5, the bias is not symmetric in sensitivity and specificity. When misclassification is nondifferential, estimated odds ratio tends to be 1 while the exposure prevalence in the control tends to be 0 or 1. Bias seems to be very complex in differential misclassification than in nondifferential misclassification that can make OR tend to or be away from the null value.

CONCLUSIONThe impact of exposure misclassification on the effect associated with exposure--disease is complicated, hence necessary to understand, to control, and to assess bias of misclassification in order to correctly interpret the results of a study.

No abstract available.
Aged ; False Positive Reactions ; *Histocompatibility Testing ; Humans ; Isoantibodies/immunology ; Keratoplasty, Penetrating ; Male ; Transplantation, Homologous

This study was aimed to analyze the results of false positive reaction in bacterial detection of blood samples with BacT/ALERT 3D system, to evaluate the specificity of this system, and to decrease the false positive reaction. Each reaction flasks in past five years were processed for bacteria isolation and identification. When the initial cultures were positive, the remaining samples and the corresponding units were recultured if still available. 11395 blood samples were detected. It is worthy of note that the incubator temperature should be stabilized, avoiding fluctuation; when the cultures were alarmed, the reaction flasks showed be kept some hours for further incubation so as to trace a sharply increasing signal to support the judgement of true bacterial growth. The results indicated that 122 samples (1.07%) wee positive at initial culture, out of them 107 samples (88.7%) were found bacterial, and 15 samples (12.3%) were found nothing. The detection curves of positive samples resulted from bacterial growth showed ascent. In conclusion, maintenance of temperature stability and avoidance of temperature fluctuation in incubator could decrease the occurrence of false-positive reaction in detection process. The reaction flasks with positive results at initial culture should be recultured, and whether existence of a sharply ascending logarilhimic growth phase in bacterial growth curve should be further detected, which are helpful to distinguish false-positive reactions from true positive, and thus increase the specificity of the BacT/ALERT system.
Automation, Laboratory ; Bacteria ; isolation & purification ; Bacteriological Techniques ; methods ; Blood ; microbiology ; Culture Media ; False Positive Reactions ; Humans

BACKGROUND: The dipstick methodology is the most fundamental urinalysis but interfered by many factors. We evaluated the effect of semen contamination on the urine dipsticks. METHODS: Thirty-two specimens for semen analysis were enrolled. After semen was directly applied on urine dipsticks, residual samples were diluted in pooled normal urine. Urine dipsticks were performed at each dilution titer. Seminal plasma separated by centrifugation of semen were also tested in the same manner. RESULTS: All semen showed positive results for blood, protein and leukocytes. The intensities of reaction for blood and leukocytes were correlated with sperm concentration. The negative conversion of blood and protein occurred at 1:100, and that of leukocytes occurred at 1:50. Seminal plasma showed nearly the same findings. CONCLUSIONS: Semen contamination of urine may cause false positive reaction especially for blood and protein on the urine dipsticks. It should therefore be considered when assessing unexplained, transient hematuria or proteinuria.
Centrifugation ; False Positive Reactions ; Hematuria ; Leukocytes ; Proteinuria ; Semen Analysis ; Semen* ; Spermatozoa ; Urinalysis

Duodenal leiomyomas are rare benign tumors of mesenchymal origin. Generally, Fluorodeoxyglucose (FDG)-PET would have a negative finding in leiomyomas. A 52-year-old man was referred to our hospital with melena. Gastroendoscopy revealed the presence of a huge submucosal tumor with ulceration at the duodenum bulb. Subsequent CT demonstrated a poorly enhanced oval mass adjoining the duodenal bulb. FDG-PET scan demonstrated an excessive accumulation of FDG in the lesion. A definitive diagnosis of duodenal leiomyoma was made on the basis of the pathologic finding of his surgical specimen. We report in this first case that duodenal leiomyma may show a potential pitfall of giving a positive FDG-PET result. Through this case, we would like to caution clinicians against PET-dependent evaluations of malignant potential of duodenal submucosal tumors.
Duodenum ; False Positive Reactions ; Fluorodeoxyglucose F18 ; Humans ; Leiomyoma ; Melena ; Middle Aged ; Positron-Emission Tomography ; Ulcer